1. Field of the Invention
The present invention relates to an energy device and a method for producing the same. The present invention also relates to electronic equipment using an energy device.
2. Description of the Related Art
The miniaturization and enhancement in performance of electronic equipment are proceeding continuously. In order to achieve the miniaturization and enhance the performance of equipment, it is necessary that various kinds of devices such as a semiconductor integrated circuit, a module, a chip component, a multi-layered substrate, a flat cable, and the like constituting the equipment are miniaturized and have enhanced performance. An energy device such as a battery also is being miniaturized and enhanced in performance along with the miniaturization of electronic equipment.
A lithium ion secondary battery that is representative of miniaturized high-performance energy devices is composed mainly of a negative collector, a negative active material, an electrolyte, a separator, a positive active material, and a positive collector. The miniaturization and enhancement in performance of the lithium ion secondary battery can be realized by providing, in parallel, the increase in energy density of active materials for positive and negative electrodes, the reduction in thickness of collectors of positive and negative electrodes, the enhancement in performance of an electrolyte, the reduction in thickness of a separator, etc.; the increase in energy density of a battery; and the assurance of safety that is becoming difficult to achieve in close connection with the above-mentioned proceeding. This enables, for example, high-performance mobile equipment to be miniaturized and driven for a long period of time.
The reduction in thickness is one of the important items among the miniaturization and reduction in weight required of mobile equipment, and for this purpose, the reduction in thickness of an energy device is proceeding. A liquid-type lithium ion secondary battery using an electrolyte solution requires measures for preventing leakage of liquid, so that the reduction in thickness involves difficulty. Thus, a thin battery using a solid electrolyte is a promising candidate. Representative examples of such a thin battery include not only a polymer battery but also a thin-film lithium ion secondary battery. The thin-film lithium ion secondary battery generally has a battery constituent layer (battery cell) including a positive collector layer, a positive active material layer, a solid electrolyte layer, a negative active material layer, and a negative collector layer in this order. The respective layers of the battery constituent layer generally are formed successively by a vacuum thin-film process such as vapor deposition.
A sheet-shaped energy device is very effective for reducing the thickness of equipment, so that it is becoming a device important in future electronic equipment.
For example, JP2002-366059A discloses a very thin portable information terminal with high visibility even at a dimly lit place, including at least an organic EL display, a plurality of IC chips, an antenna coil for communication, a key switch for input, a sheet-shaped energy device, and the like. According to JP2002-366059A, a transparent substrate of the organic EL display is mainly composed of a polymer, the IC chips are formed to be thin, and the like, whereby a portable information terminal that is not easily broken by bending can be obtained. Furthermore, JP2002-366059A describes that highly water-resistant materials are used as constituent materials for the transparent substrate and a support substrate or a multi-layered wiring substrate to be a core of the portable information terminal, and the organic EL display is sealed with these materials, whereby the display can be prevented from being degraded due to the moisture absorption and be highly reliable.
By using a sheet-shaped energy device as described above, the reduction in thickness and weight of mobile equipment and the like can be achieved. However, the energy device occupies a large area in electronic equipment due to its sheet shape, so that there is a great constraint on the arrangement of other devices and a wiring substrate. Particularly, in the case of assuming high-frequency equipment, there is a possibility that lengthy wiring may degrade the reliability of the equipment. Measures for eliminating such a demerit while maintaining the characteristic thinness of the sheet-shaped energy device are required.